Proximity measuring of the rotating shaft of a subsea pump or subsea compressor can give valuable information of the running conditions of the pump or compressors. Proximity measurement of rotating equipment is known in systems operating in low pressure—such as an atmospheric environment found topside. However, proximity sensing of a rotating shaft is much more challenging in subsea pumps or compressors since the process fluid pressures can be in the range of 15-20 kPsi, and where associated electronics needs to be protected against the seabed pressure.